Block diagram outline
This assembly, DTB, is composed below circuit blocks. Below is showing outline of each circuit blocks.
DIGITAL FRONT END
This block turns Digital RF signal from connected cable or antenna, and converts it to IF frequency,
44MHz.
In case of cable system, the OOB, Out of Band signal, is passed though and converted by the Down
Converter IC in subsequent circuit.
QAM/VSB/QPSK DEMODULATION（BCM3517）
This block demodulates IF signal, 44MHz, from
the
Tuner, and converts it
into a
Transport stream,
and
is
send
to the
BACK END IC.
OOB signal, converted to 50 MHz IF signal, is treated by QPSK modulation, and the data and clock, come
from OOB, go to Cable Card (POD) block.
VIDEO DECODE (VDEC)
This block decodes Analog composite video signal, come from Main Board, and treats it as 3D Y/C
separation in order to convert 656 Video Format, and sends it to BCM7038. In addition, this block has the
function of VBI data slice and sends BCM7038 the data such as EPG data and CC data via I2C.
Audio AD conversion (AD Block)
This block converts Analog audio signal to Digital and sends to BCM7038.
POD I/F
This block adopts PCMCIA slot and it is available to see scrambled TV program by inserting this portion
Cable Card, which is assigned by Cable Operator. POD I/F IC contains Card Module I/F and Digital Video
Stream I/F, and controls the scrambling with communicating between these I/F and BCM7038. OOB signal
sends SI information to Cable Card.
BACK END IC（BCM7038）
This is the system IC which is 1 chip and is created as the application of Cable System and DTV system.
This IC has functions such as HD/SD MPEG Decode, graphic processing, scaling processing, and D/A
processing, and controls DDR-SDRAM for System memory.
This IC also has a function to hold the audio data in memory in order to synchronize between audio and
video.
IEEE1394
There are 2 I-Link ports, and it is available to connect with Digital AV products, supporting I-Link.
DDR SDRAM
There are 4 DDR SDRAMs, 256Mbit 166MHz, 128Mbyte. These connect to BCM7038 by 64bit data bus.
G-LINK PORT
This port is connected IR controller and controls analog VCR.
Also, This port has serial port which is used by downloading software for only TV-GUIDE..
FLASH,EEPROM
Data storage for application of products. Data capacity is 32Mbyte.
EEPROM has several data for settings, and DTB is operated by their data.
DIGITAL VIDEO OUT
This block converts the format of digitally-processed YCbCr signal which come from BCM7038, and sends
it to Main Board.
POWER REGULATOR
This block generates DC 9V, 5V, 3.3V and 1.8V for analog and digital circuit by using regulator.
This block also generates DC 3.3V, 1.8V and 1.2V by using DDC and regulator.
9
